I don't know what you're doing with it, but it sounds fun.
Here's a little AHK script doing most of the things you want. Perhaps you'll find it useful until someone provides a better solution or enhances this basic script. It works fine on my system. The sound file is just started and sent to the registered sound player. On my system it's Winamp. It communicates via the Tray.
> So if I'd set "min" to 10 minutes and "max" to 30 minutes
> an option to set the volume
> ability to have it play more than one file
Done. Edit the file "randomplayer_songlist.txt" and add with full path song files. Sample entries provided.
> (in ABC order or randomly)
Randomly. The script kinda remembers the tracks played in a file called "played.txt" and won't repeat until all files in songlist.txt have been played.
> an optional toaster
Sorry, no. Install http://www.cdartdisplay.com/
> or tray area bubble notification that announces that it will play the/a mp3 in x seconds
> (the amount of seconds being customizable)
Done. Load the script in notepad. There're some parameters to configure.
> low CPU usage is much appreciated!
Guess it's done... but this isn't really my doing. AHK power... ;-)
EDIT: Download moved to my last post in this thread